The inverter (or inverters) your solar system uses is the under-appreciated sidekick for those sleek photovoltaic panels on your roof. Like the Watson to a Sherlock, the inverter takes all of the amazing work going on at the forefront of the operation and turns it into something usable. Put simply, the inverter converts the direct current (DC) energy produced by your solar panels into alternating current (AC) energy your building's occupants can use.
A central or string inverter converts the collected power from all of the panels in an array (a solar sytem can have multiple arrays, depending on its size). These inverters are more efficient and powerful overall. They are not installed on the roof due to its exposure to the elements, and are instead attached to the side of a building or housed in a separate room.
Conversely, micro-inverters can be found under each panel in a system. Each micro-inverter inverts the energy of the panel to which it's connected.
Throughout our history, we have installed nearly every type and brand of inverter available, including string inverters, micro-inverters, and a newer inverter type called optimizers. We quickly realized that each type had its own benefits and drawbacks, and after installing over 1,000 systems, we developed an opinion about which type lasted longest and performed best.
While string inverters were an established technology that did not require rooftop components, having a single point of system failure and the absence of panel-level monitoring proved challenging. Micro-inverters resolved some of these issues, but came with their own headaches (see below). Eventually, we decided to start using SolarEdge optimizers because they represented the best of both worlds. They also come with a few added benefits of their own, including sensitivity to low light conditions and the ability to connect to Tesla battery backup systems.
Why We Went with Optimizers
Optimizers are wonderful because, paired with a sturdy central inverter, they combine all of the best aspects of micro-inverters and string inverters. Among all types of inverters, optimizers can best boost solar system output and fight inhibiting climate factors. They maximize the power output of each module on the DC side before sending it to the inverter below, rather than having multiple inverters baking on the roof. Here are a few other advantages:
- Individual panel monitoring allows you to track the system's total and single panel output, making it easy to see if one module or the whole system has an issue.
- Their simple design means that there are fewer cheap components that could break down under harsh rooftop conditions, making optimizers the highest-efficiency inverter type. Studies conducted by solar technicians found through side-by-side testing that SolarEdge optimizer efficiency can be up to 10% greater than that of micro-inverters, leading to sizable energy savings over the 20-30 year lifespan.
- Don't fear the shade, because optimizers allow each panel to operate regardless of the potential shade on another. Even in full sun, optimizers have been found to boost production by 3-5 percent!
- Tesla-grade Solaredge Optimizers are Tesla-ready, and were chosen by Tesla as a partner in growing the future of battery backup accessibility and efficiency.
Problems with Micro-Inverters
Clipping: Micro-inverters automatically clip the amount of power they will produce at whatever wattage they are rated: 190, 215, or 250. The rating of your micro-inverter limits the wattage that your system will produce. So if you install a 270-300 W module with 215 or 250 W micro-inverters, it can only produce up to 215-250 Watts.
Electrical Components and Heat: Imagine having 466 parts on your roof at 150 degrees, as opposed to 186 parts on your roof. Due to the number of complex electrical parts that make up micro-inverters, they often break down in the extreme heat of a roof beneath a panel. Micro-inverters also use electrolytic casings, which degrade more easily, while optimizers use ceramic casings, which hold up better in high heat.
Joule Client Repairs: Over the years, before optimizers became available, we installed a lot of micro-inverters. To date, the majority of our service issues are related to micro-inverter failure.
If you're still agonizing over your choice of inverter, don't worry. A lot of clients get swept up in this decision. Regardless, you can rest assured that a Joule Energy account manager will help you every step of the way as you plan out your solar system.